Variable high resistance



Feb, 10,1925. 1,526,191

c. E. vAwTER VARIABLE HIGH "RESISTANCE Filed July 12, 1922 INVENTOR BY zE .g TTORNE Patented Feb. 1o, 1925.

CHARLES E. VAWTER, OF PHILADELPHIA, PENNSYLVANIA.

VARIABLE HIGH RESISTANCE.'

Application led July 12',

To all whom it may concern:

Be it known that I, CHARLES E. VAwTEn. a citizen ot the United States,residing at Philadelphia` in the county ot Philadelphia. State ofPennsylvanim'have invented certain new and useful- Improvemcnts inVariable High Resistauces: and I do hereby declare the following to be afull., clear, and exact description of the invention, sueh'as willenable others skilled in the art to which it appertains to make and usethe' saine.

This invention relates tovaiiable resistances, and more particularly tovariable high resistances especially adapted to bcused as grid leaksandfor other purposes in connection with rad-io systems.`

lIn operating radio systems it has been ound.-v necessary to providelsomcmeans whereby the negative charge which 'accumulates on the grid'of the vacuum tube may -be dissipated. It vacuum tubes are used withouta suitable grid leak, the operation is not always satisfactory due tothe choking effect of the negative charge which accumulates on .thegrid.

One of the bestways of carrying off the negative charge of the grid isto provide a high resistance in the grid circuit. A high resistancesuitable for this purpose should bc easily adjustable. and its charactershould be such that when it is once adjusted the resistance does notvary.y The effect of the high resistance is to provide a means wherebythe negative charge o the grid may'bc dissipated at a definite rate.,vThe Value of resistance required in any given case de'-l pends uponvarious factors, such as .the character or" the vacuum tube employed,the voltage impressed on the vacuum tubev` the current in the filamentand the degree of vacuum. The resistance'serves not only as a lreadymeans for dissipating the negative charge, but also as a means forgreatly increasing thc utility of the vacuum tube.

One of the objects ot this invention is to provide a high resistancewhich may be easily adjusted, the resistance being of. such a characterthat When it is adjusted to any given value it remains constant at thatvalue. A further object is to provide an .inexpensive variable highresistance which possesses qualities superior to those of any other highresistance.

Another object is to provide a variable high resistance unit of animproved..con struction, such that theresistance unit may 1922. SerialNo. 574,474.

be readily attached to the terminals of a grid condenser, thus providinga combined condenser and grid leak of improved construction andcharacteristics.

T hc means by which the above mentioned objects and various others areattained will .be apparent from the following detailed. descriptionwhich is to bc taken in conjunction with the accompanying drawings inwhich-A Fig. 1 is a top plan View of the improved resistance unitshowing the manner in which it is attached to a condenser;

Fig. 2 is a longitudinal section taken on line 2-2 of Fig. 1 showing theconstruction of the resistance unit and of the condenseri Fig. 3 is anenlarged transverse section taken on line 3 3 of Fig. 1 showing thedetails of construction.

Fig. 5 is an end elevation of the structure shown 1n Fig. 4.

Referring to the drawings, and more particularly to Figs. 1 to 8, itwill be noted that the improved resistance unit comprises primarily acontainer 1, which in the form shown consists of a tube of insulatingmae terial. This tube 1 may be made of glass. or ot any other suitableinsulating material. The inside of they tube 1-is filled with a suitablepaste material which constitutes the resistance element ol the unit.This paste 2 may be composed of finely divided carbon mixed with tallow,or it may be made of other suitable materials. For example, potassiumbichromate may be substituted for the carbon. In fact, any substancenfay be used which is of a semi-huid nature and possesses a lowelectr-ical conductivity which does not vary when the resistance vof theunit is adjusted to any given value. y

lIDlectrical contact is made with the paste 2 by means of two metallicend pieces 3 and 3. which, as shown in the drawing, are

adapted to enclose the ends of the tube 1.

These, endpieces may have extensions 4 provided thereon by means ofwhich the resistance unit` may be mounted on any suitable base. One ofthe. end pieces, for example,

the end piece designated as 3 is provided with a small hole 5 concentricwith the inf.v`

Plunge tube l.

The resistance 'of the unit. maybe considered as composed ot two.Components.

One,eomponentis the resistance of that dorf tion of the paste which isnot penetratec by `the pin 65 and the 'other oomponentis the resistanceof the remainingv portion of the -unit comprising that portion of thepin within .the tube l, and the paste surroundfing that portion of thepin. It is evident does contain 'the metallie pin 6.

that. the' resistance of that'portion of the tube which does not containthe pin is higher than the remaining portion Whirh It is thus 'apparentthat the resistance of the tube may be varied hy changing the. positionof the pin 6." For example, when the pin 6 is'moved to the dottedposition' shown .in Fig'. 2, the resistance of the unit is increased,due to the decrease in length of that portion of the pin which is Withinthe tube 1.'

` 'The resistance unit shown in Fig. comprises atuhe l containing a highresistance paste similar tothat in the tubol of the unit shown in Figs.1 3.- The tuhe l is preferably made of fiber or other insulatingmaterial, and has metalen/d pieces 1.3 and 1B. These end pieces i3 and13" are adapted to he slipped over ther ends ot the tube 1"With apressed vtit, the tube l being first iled with the' paste 2. One of theend pieces7 for example, 13 has a smaii hole or passage 14 in the endthereof.

The resistance unit shown in Figje is ot the cartridge type and may hemade ot standard size to fit any ordinary grid leak sockets orreceptacles such as shown at 4i. The'unit-may hev used as a fixed. highresistance, or it may be used as a variahie re sistance.' When used as afixed resistance the opening or passage 14 is 'preferably sealed. Whenthe unit is used ".f a Variable resistance, a needle 6a. simila-r'totlieneedle 6 of Figs. 1-3 mayhe used, the resistance being varied h'yvaryingth'e'position oi" the needle. I

I have found that a variable resistance ConstiiciedI ,mi the mannen@l'described here possesses 'qualitiess'iipe-rior to those ot any othertypeo vaniablerhigzh resistance. The resistanceot the runit/maybe easilyadjusted to any desiredyaliie and 'when the' resistance hasgheenadjusted Ito any given value.

'it remains oolistantjfhe construction of Vthe resistanceunit-isjvery.-,simpie and, theretore. resistanees otthisstype may oemade in large quantities at yery low cost. Each of .theeonponentfpafrts. ot `the resistance unit is easy to manufacture. `Forexample. the' tubeconsists merelyof 'a short length ot ordinary tubingtof anxr suitahleAo-haraeter, such as gia-eser Aber `lterminais proyunitshown"fin1f,Figs. i to 3.

maaier 'only ordinary skill is required to the elements in any desiredproportions.

The improved resistance unit may he made ot suoli dimensmns that it maybe readily attarlied to the terminals of a. condenser.

inthe-Combined condenser and resistance the improved variable resistanceshown attached to the terminals ot an improred condenser, the condenserheilig m the ti'pe disclosed 1n InyopendingY appliration. .Qerial No.562.963, r'iledA May i3. 1922.

As described inmi eooendinn' ap ilieation.

the improved eondcnser comprise. piumiity of armatures S separated hf:thin strips of dieieetrir materia-l. The armatures and strips oi'dieieetrio material are enclosed-in a metal casing; 9. the sides or"which are pressed. to clamp the armatures in position Tabs i() areprovided at thoends.

ti fghti y. oi the armatures S. the tahs heine' connected so that theyform the terminals ot the condenser. In the form shown in thedrawing.

the condenser comprises two armatures oniy.

A strip lfi ot halteiie or other suitable in srdfitinef material isprovided between the extensions Liandr of the resistance terminais. andthe lcondenser terminais, the purpose ot' this insulating; materialbeing to prevent eleetricai Contact` between the con denser casingy andthe resistance element. The several eiements ot the composite unit areNfastened together hy any suitable means, surh as .the holte 12. Theboit-s 'i2 aise serve as a means tor connecting the improved unit-qinroirouit with the other elements of the grid circuit.

From the shove description it shouid he 'apparent that the present'invention provides an improved vnriahie hie/h resistance element whichpartieniarly adapted to he usedV in connection with n'ireiess systems.The, improved resistance is partieniariy adapted 'to he used as aeridieak. and as a 'variable hie'h resistance shunt 'for ny-passingoliject-i'onahie high .frequency or momentary current-s.

' it willho nn'derstod that the'invention is not limited to theparticular"emhodiments .shown and described. init is intended to in!olude suoli niodinaiiions thereof as tali within the scope of the'appended claims; and the proportion'sotthe `arious parte and themateriais ofwvhieh" they are made may he varied Wit-hout departingrointhe scope of the inn ntion .as defined in 'the appended ciaiinsL 4 YY i x i daim, f 1. A. variable resistance nniteomprisin'g a .container.a resistancemateriai Within 'so' i ino anti arranged at the reepeeseidntainer for transmitting enr-rent to and Sinin said resistance ina.'-eieel, en electrically conducting member .eliclnnlg' mounted in one ofSaid oonclneting terminals :incl extending Within said con# tainer inteelectrically conducting relation with-the resistance materiel therein,whereby said member is adjestablev longitudinally of eziicl Containerte. @ense ifnrying preportione said resistance ineteriei to be traversedby the eleetrie current passing between the tern'iinale ef the unit.

i vnrinlile resistance unit comprising a tnbnler cent-einer, resistancemateriel Wieliin said eontaiiier, conducting termin-ile at illerespective enfle of said container -ler .nsmitting enrrent to end fromSeid re- ',tenee materia-l, an electrically eonclnoting nien sliclablymounted for longitudinal movement in the enel of one of said een-I.neing tesininels and exteinlinf into eleo- 'ieailg'eondneting relationwith the resistneegnmteriei Within the container to thereupporte r-saiclcontainer, said supports y very the resistance of the unit upon albeingadapted to engage the ends ef eei Container :incl one of said supportshaving a, hole for the passage of seid adjustable member. l -Y 3. Avariable resistance 'unit comprising container, a resistance materielWithin said eontainer, conducting terminals et the respective ends ofsaid container' for transmitting onrrent to and from said resistancematerial, the said respective conducting terminals lia-ving taperedextremities, en. electrically conducting member assing through one ofsaid conducting terminals at substantially the apex of the taperedportion thereof and extending Within Said container into electricallyConducting relation with the resistance material therein, whereby saidnienilier is slidable longitudinally of said container to cause varyingproportions of said resistance material to be traversed by the electriccurrent passing between the terminals of the unit, and conductingSupports for said container having apertures for receiving the taperedends of said eontainer7 and permitting the passage of said conductingmember.

In testimony whereof I aiiix my signature.

CHARLES E. VAWTER.

